1. Technical Field
The present invention relates to a fluid injection device including an injection pipe and a suction pipe.
2. Related Art
A method for excising, incising, and crushing a living tissue by using a fluid injection device has preferable characteristics as a surgical instrument such as capabilities of preventing heat damage and preserving blood vessels and other capillary tissues. When an operation is performed using the fluid injection device, injected liquid, excised tissues or the like which remains on the portion of surgery becomes an obstacle for securing vision in some cases. As a technology for overcoming this problem, such a fluid injection device further including a suction pipe capable of removing liquid or excised tissues by suction is known.
As an example of this type of fluid injection device, a device which has an injection pipe for injecting high-pressure fluid as a pipe disposed within a suction channel of a suction pipe in such a position as to be concentric with the suction channel has been proposed (see JP-A-1-313047).
Another example of the fluid injection device currently proposed includes an injection pipe for injecting high-pressure fluid as a pipe inserted eccentrically with respect to the inner circumferential surface of a suction pipe (see JP-A-6-90957).
A further example of the fluid injection device sharply changes the volume of a fluid chamber by using a volume varying unit to convert fluid into pulse flow and inject the pulse flow through an injection opening as pulses at high speed (see JP-A-2008-82202).
According to the technology disclosed in JP-A-1-313047, the inner circumferential surface of the suction pipe and the outer circumferential surface of the injection pipe are concentrically disposed. Thus, the size of the suction channel at a suction opening (the length of the clearance between the inner circumferential surface of the suction pipe and the outer circumferential surface of the injection pipe) becomes half of the difference between the inside diameter of the suction pipe and the outside diameter of the injection pipe. In this case, it is difficult to remote excised tissues larger than the size of the suction channel at the suction opening by suction. When the diameter of the suction pipe is increased to secure the sufficient size of the suction channel, the vision for surgery is narrowed.
According to the technology disclosed in JP-A-6-90957, the injection pipe is inserted eccentrically to the inner circumferential surface of the suction pipe. In this case, the size of the suction channel corresponds to the difference between the inside diameter of the suction pipe and the outside diameter of the injection pipe, and thus becomes larger than the size of the suction channel in the concentric structure shown in JP-A-1-313047 when the suction pipe and the injection pipe have the same diameters as those in the concentric structure. However, there is a possibility that vibration is generated at the top end of the injection pipe, that is, in the vicinity of the injection opening at the time of injection of high-pressure fluid. In this case, injection of fluid toward the target surgery portion becomes difficult.
Moreover, according to the structure which inserts the injection pipe eccentrically to the suction pipe as the structure shown in JP-A-6-90957, the position of the injection opening cannot be directly recognized by visual check. Thus, injection of fluid to the accurate position of the target surgery portion is difficult.
According to the fluid injection device disclosed in JP-A-2008-82202, excision can be achieved by using a smaller amount of fluid than the amount of high-pressure fluid injected as continuous streams used by the methods shown in JP-A-1-313047 and in JP-A-6-90957. In case of the structure disclosed in JP-A-2008-82202, however, there is a case in which a suction pipe is required for improvement of visual recognizability of the surgery portion or for removal of excised tissues by suction. In this case, the injection pipe can be inserted eccentrically to the inner circumferential surface of the suction pipe for increasing the size of the suction channel as in the structure shown in JP-A-6-90957. However, when fluid is injected as pulses in this structure, it is expected that vibration of the injection pipe becomes larger than vibration generated by continuous flow injection.
When vibration is generated on the injection pipe, abnormal noise is produced by contact between the injection pipe and the suction pipe. Moreover, when the suction pipe is resonated by vibration generated at the top end of the injection pipe (injection opening), injection of fluid toward the surgery portion becomes difficult.